ARDS leads to a buildup of fluid in the air sacs (alveoli). This fluid prevents enough oxygen from passing into the bloodstream.

The fluid buildup also makes the lungs heavy and stiff, which decreases the lungs' ability to expand. The level of oxygen in the blood can stay dangerously low, even if the person receives oxygen from a breathing machine (ventilator ) through a breathing tube (endotracheal tube).

ARDS often occurs along with the failure of other organ systems, such as the liver or kidneys . Cigarette smoking and heavy alcohol use may be risk factors.

Symptoms:

Symptoms usually develop within 24 to 48 hours of the injury or illness. Often, people with ARDS are so sick they cannot complain of symptoms. Symptoms can include any of the following:

Difficulty breathing

Low blood pressure and organ failure

Rapid breathing

Shortness of breath

Exams and Tests:

Listening to the chest with a stethoscope (auscultation ) reveals abnormal breath sounds, such as crackles, which may be signs of fluid in the lungs. Often, blood pressure is low. Cyanosis (blue skin, lips, and nails caused by lack of oxygen to the tissues) is often seen.

The goal of treatment is to provide breathing support and treat the cause of ARDS. This may involve medicines to treat infections, reduce inflammation, and remove fluid from the lungs.

A ventilator is used to deliver high doses of oxygen and continued pressure (positive end-expiratory pressure, or PEEP) to the damaged lungs. Patients often need to be deeply sedated with medicines. During treatment, doctors and nurses make every effort to protect the lungs from further damage.

Support Groups:

Many family members of people with ARDS are under extreme stress. Often they can relieve this stress by joining support groups where members share common experiences and problems.

Outlook (Prognosis):

About a third of people with ARDS die of the disease. Those who live usually get back most of their normal lung function, but many people have permanent (usually mild) lung damage.

Many people who survive ARDS have memory loss or other quality-of-life problems after they recover. This is due to brain damage that occurred when the lungs were not working properly and the brain was not getting enough oxygen.

Possible Complications:

Failure of many organ systems

Lung damage (such as a collapsed lung--also called pneumothorax ) due to injury from the breathing machine needed to treat the disease

Usually, ARDS occurs during another illness, for which the patient is already in the hospital. In some cases, a healthy person has severe pneumonia that gets worse and becomes ARDS. If you have trouble breathing, call your local emergency number (such as 911) or go to the emergency room.